http://papers.ssrn.com/ says it has 575,470 scholarly articles and that there have been 12,975,032 article downloads over the last 12 months. Many articles are for free, some cost $5, some cost over $1 per page, and some have an abstract but the article is not available for any price. Many, but not all, of the articles are about the United States. I'm interested in Economics and Political Science. So far I downloaded 34 articles totaling 1,404 pages, which is an average length of exactly 41 pages. The articles are in PDF format. In addition, there are 18 topics with articles that you can pay for. 3 of the topics are free, and the other 15 range from $45 to $95 per year. It costs $860 per year to subscribe to every topic.